Thanks borys,
Could you give the schematic so i could this little layout modification under eagle? I have some KSC3505/KSA1381 and MJL4281/4302 in instock as Match BC pair i think...
Marc
Thanks. By examinating your layout i can see 2 straps that's could be suppress. I will try a Sanken MT200 layout...Nice sharing at all.
Marc
Good job borys.
Did you assemble any blameless type of an amp up to nowadays? How's VSSA compare to voltage feedback amps to your opinion?
borys' FFT post for the BJT version, shows relatively high odd harmonic distortion, especially 7th, 9th, 11th and 3rd. This is the kind of profile that many Audio gurus try to avoid to get a more euphonic sound; Nelson Pass, John Curl, Dean Hughes, Hiraga are some of the examples.
Is there a way of either reducing the odd harmonics or relatively increasing H2? IIRC I have seen some techniques around here which load the input pair collectors with a resistor to ground.
Is there a way of either reducing the odd harmonics or relatively increasing H2? IIRC I have seen some techniques around here which load the input pair collectors with a resistor to ground.
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Do not worry about higher order harmonics products, these are my sound card artefacts.
I have measured symasym apex ax14 and plenty vssa different variants. On all my measurements there are the same artefats present (all amplifiers at the same place).
I must upgrade or buy different sound card for measurements.
LC
I do not know how it would compare to votage feedback amp at the moment I would have to upgrade my speakers and do A and B test to compare.
One I can say the amp is very very good, very fast and tight bass.
Next I am going to measure DF - but need some bigger transformer for that.
I have measured symasym apex ax14 and plenty vssa different variants. On all my measurements there are the same artefats present (all amplifiers at the same place).
I must upgrade or buy different sound card for measurements.
LC
I do not know how it would compare to votage feedback amp at the moment I would have to upgrade my speakers and do A and B test to compare.
One I can say the amp is very very good, very fast and tight bass.
Next I am going to measure DF - but need some bigger transformer for that.
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The above toshibas sure they can be used, but in bit different circuit, circuit has to be the same as for renesas laterals, the only difference would be biasing becouse there are two Ugs versions of toshibas availible.
I will check later (pinout) but I think You can use one of fet hex board and modifi slightly bias stage (do not solder mosfet and put one or two joints)
Hello
You know the Renesans or Hitachi is LatFet while the mentioned Toshiba is not.
Toshiba has the same pin out than the Hexfet.. Some people built F5 with the Toshibas instead Hexfet with better result. I purchased my matched Toshiba for that project but I think at these project it would be better use for them.
Probably need some small adjustment at bias and may need lower Drain voltage than hexfet..
I built these topology with darlingtons more than 20 years a go. I do love the sound a lot but has some stability issue with the bias drifting specially with higher bias set up.
Probably I introduce these topology on the forum, nice to see so many different project came alive.
I do want to follow these thread, I'm open to learn new think, also would be great to see someone would bring together a stable project with these topology using bipolar power transistors.
To me the biggest problem I do not own a scope so modifying a circuit not the easiest task with out a scope.
Thanks for your answer
Greetings Gabor
I do have several LatFet project so I would be more interest to use those Toshibas..
No, the Toshiba's are vertical MosFets (unlike Renesas, Alfets, Exicons and Magnatecs which are Lateral Mosfets) and are very much suited for Fet-hex explendit circuit using bias servo. Toshiba never produced Lateral Mosfets. But Toshiba's are great devices anyway and will give excellent results in Fet-hex explendit circuit if you can find them. Proper bias for these devices is 145mA.
I didnt know that they arent laterals, thanks. But in datasheet they look realy superb, very linear. I have ordered couple of them just for try.
these are usually listed as "obsolete", at least in the US, but there is someone (NicMac) here on diyaudio who is selling matched sets for the F5 and F5T. So if u have a conventional source for those, I am sure others would be interested too...http://www.diyaudio.com/forums/parts/237953-2sk1530-2sj201.html
In fact, John Linsley Hood proved these vertical mosfets by Toshiba to be the most linear devices, more linear than BJT and LatMosfet, when used in circuits (not per se) in his famous experiment with classic Lin topology.
http://www.diyaudio.com/forums/parts/237953-2sk1530-2sj201.html
Very much interested in conventional source!
http://www.diyaudio.com/forums/parts/237953-2sk1530-2sj201.html
It doesn't have to be Toshiba J201/K1530. There are also Toshibas J200/K1529 and J618/K3497 (in TO3P package). But I guess these are also difficult to find.
I have made some tests today.
Cause bd139/140 pair is not very high voltage friendly I decided to put mje340/350 (Yes I know that people do not like them), I only forgotten to desolder compensation caps (mje are slow enough to work without them).
Bellow test results , 8R load. Just tu compare last one is symasym square at 20kHz.
I think this topology is wort to develop further.
Can someone can give me some advice please, would be better off to replace the vas transistors with the same as in driver stage - I mean 2SC4793/2SA1837 pairs in vas and in driver stage ??
I do not want to put some sanyo tranies ( I know them would be great) cause I need some easy availible tranies.
Thanks
Cause bd139/140 pair is not very high voltage friendly I decided to put mje340/350 (Yes I know that people do not like them), I only forgotten to desolder compensation caps (mje are slow enough to work without them).
Bellow test results , 8R load. Just tu compare last one is symasym square at 20kHz.
I think this topology is wort to develop further.
Can someone can give me some advice please, would be better off to replace the vas transistors with the same as in driver stage - I mean 2SC4793/2SA1837 pairs in vas and in driver stage ??
I do not want to put some sanyo tranies ( I know them would be great) cause I need some easy availible tranies.
Thanks
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